Conventionally, there is proposed a technology in which a target value is set for the amount of electric power to be used by a consumer and the set target value and the amount of electric power used by the consumer are displayed for comparison, thereby causing a consumer to be aware of reducing the amount of electric power to be used.
For example, Japanese Patent Application Publication No. 2005-234746 discloses that a unit term such as one year or one month is divided into a term such as one month or one day, a target value is set for every divided term, and an energy amount to be consumed from this time is predicted from the target value of each divided term. Specifically, a ratio of the actual value to the target value is calculated as a target rate for every divided term, and an energy amount from this term is predicted using transition of the target rates. In addition, an accumulated value of the energy amount in a unit term from the predicted energy amount is obtained, and propriety of attaining the target is predicted on the basis of the accumulated value.
The abovementioned document states that data of the amount of electric power of each energy management target may be collected, and thus suggests not only a case where the energy amount is managed for only one system before being branched from a distribution board but also a case where the energy amount is individually managed for each energy management target.
Meanwhile, the abovementioned document does not suggest a technique of setting a target value, and in particular, in the case the energy amount is individually managed for each energy management target, does not state how to set each target value.
Recently, a reduction target of the amount of electric power may be set due to a request from an electric power company or the like in some cases. Alternatively, a consumer him/herself may set a reduction target of the amount of electric power in some cases. Because such a reduction target is determined on the amount of electric power purchased from the power supply system of the commercial power source, it is difficult for the consumer to set each target value of the amount of electric power to be used in an individual branch circuit or an individual load device, in order to attain the reduction target. In other words, setting a target value of each branch circuit or each load device in order to reduce the amount of electric power gives rise to a large burden to the consumer.
Moreover, managing only a reduction target with respect to the overall amount of electric power of the consumer is likely to cause overages or shortages of the amount of electric power to be used because the amount of electric power which can be used for each branch circuit or each load device within the range of the reduction target is unknown. As a result, there arises a problem that the amount of electric power is reduced by 5% or 20% regardless of a reduction target being set to 10%.